Eli Zaretskii <eliz@gnu.org> writes:

>> From: Andrea Corallo <akrl@sdf.org>
>> Cc: 48578@debbugs.gnu.org
>> Date: Tue, 25 May 2021 12:34:27 +0000
>> 
>> +  /* Use `file-truename' or fall back to 'realpath' `expand-file-name'
>> +     when the first is not available.  (`file-truename' is not
>> +     available only for a short phases of the bootstrap before file.el
>> +     is loaded).  */
>> +
>> +  if (NILP (Ffboundp (intern_c_string ("file-truename"))))
>> +    {
>> +#ifndef WINDOWSNT
>> +      char *file_normalized = realpath (SSDATA (filename), NULL);
>> +#else
>> +      char *file_normalized = ??? ;
>> +#endif
>> +      filename = Fexpand_file_name (build_string (file_normalized), Qnil);
>> +      xfree (file_normalized);
>> +    }
>> +  else
>> +    filename = CALL1I (file-truename, filename);
>>  
>>    if (NILP (Ffile_exists_p (filename)))
>>      xsignal1 (Qfile_missing, filename);
>
> Thanks, I will try that.  But why not use realpath at all times, even
> if file-truename is available?  They do the same thing, AFAIK, no?

AFAIK yes but the file-truename implementation didn't look sufficiently
trivial to be sure they are really equivalent with the quick skim I had.

I agree with the idea of using always one (realpath), should be also
easier to ideantify issues in case.

Attached the updated patch.

  Andrea